In electronics, an opto-coupler, also called an opto-isolator, photocoupler, or optical isolator, is an electronic device designed to transfer electrical signals by utilizing light waves to provide coupling with electrical isolation between its input and output. The main purpose of an opto-coupler is to prevent high voltages or rapidly changing voltages on one side of the circuit from damaging components or distorting transmissions on the other side.
Currently, an opto-coupler includes a source (emitter) of light, usually a near infrared light-emitting diode (LED), that converts an electrical input signal into light, a closed optical channel (also called dielectrical channel), and a photosensor, which detects incoming light and either generates electric energy directly, or modulates electric current flowing from an external power supply. The photosensor can be a photoresistor, a photodiode, a phototransistor, a silicon-controlled rectifier (SCR) or a triac. Because LEDs can sense light in addition to emitting it, construction of symmetrical, bi-directional opto-couplers are possible.
It would be desirable to improve opto-couplers by minimizing the current footprint, inefficiencies with current opto-couplers and to provide easy and economical manufacturing techniques.